High voltage bushing with removable connector and locking plate

ABSTRACT

D R A W I N G A HIGH VOLTAGE BUSHING FOR ELECTRICAL APPARATUS SUCH AS A TRANSFORMER. THE BUSHING IS HOLLOW AND HAS PROVISIONS FOR RECEIVING EITHER A FUSE CONNECTOR OR A SOLID CONNECTOR. A LOCKING PLATE IS PROVIDED WHICH MOUNTS ON THE TERMINAL PLATE OF THE BUSHING AND ENGAGES THE CONNECTOR, PREVENTING WITHDRAWAL OF SUCH CONNECTOR WHILE THE LOCKING PLATE IS ATTACHED TO THE TERMINAL PLATE.

March 20, 1973 H, HUCKO ET AL 3,721,946

HIGH VOLTAGE BUSHING WITH REMOVABLE CONNECTOR AND LOCKING PLATE Filed Dec. 2, 1971 2 Sheets-Sheet l liiiii 1llI;ii..... miiuly V llllllllll II t Ali W My) W150? March 20, 1973 HUCKO ET AL 3,721,946

HIGH VOLTAGE BUSHING WITH REMOVABLE CONNECTOR AND OCKING PLATE Filed Dec. 2, 1971 2 Sheets-Sheet 2 United States Patent 3,721,946 HIGH VOLTAGE BUSHING WITH REMOVABLE CONNECTOR AND LOCKING PLATE Henry Hucko and Henry T. Lusignan, Pittsfield, Mass, assignors to General Electric Company Filed Dec. 2, 1971, Ser. No. 204,095 Int. Cl. H01r 13/54 US. Cl. 339-75 R 7 Claims ABSTRACT OF TIE DISCLOSURE A high voltage bushing for electrical apparatus such as a transformer. The bushing is hollow and has provisions for receiving either a fuse connector or a solid connector. A locking plate is provided which mounts on the terminal plate of the bushing and engages the connector, preventing withdrawal of such connector while the locking plate is attached to the terminal plate.

BACKGROUND This invention relates to high voltage bushings for electrical apparatus and more particularly to a high voltage bushing having a removable connector and provided with a locking plate to prevent premature removal of such connector.

As is well known to those skilled in the electrical apparatus art, such as the transformer art, high voltage bushings are provided on such apparatus as the means of entry for the electrical power to the apparatus. Often the high voltage bushing is provided with a fused member which forms the high voltage connector through the bushing. The fuse is usually removable to provide replacement, if necessary. Other bushings are provided with a solid connector member which may also be removed to provide a visible indication that power has been disconnected from the apparatus prior to allowing utility personnel to work on such electrical apparatus.

In most present day electrical apparatus, the fuse or connector of the bushing must be removed dead, that is, without the line being energized, since these bushing members do not have any switching capability. However, even when the secondary load is removed from such electrical apparatus, a magnetizing current is present in the apparatus which is sufiicient to damage the threads or bayonet connection of either the fuse or solid connector when such connector is being disconnected. It is, therefore, considered desirable to disconnect the high voltage cables from the bushing prior to removing the fuse or solid connector. Obviously, this can be done by an internal switch or an external disconnect. As will be well understood, an external disconnect would be much less costly than internal switching. Of course, it is also desirable that the external disconnect prevent removal of the bushing connector prior to operation of the external disconnect.

It is, therefore, one object of this invention to provide an external disconnect for a bushing to lock a removable bushing connector in place.

A further object of this invention is to provide a locking plate for a bushing connector, the locking plate con taining the high voltage cables.

A still further object of this invention is to provide an external disconnect for a high voltage bushing in the form of a locking plate that prevents removal of the bushing connector without first removal of the locking plate.

SUMMARY Briefly, in a preferred form, this invention comprises a bushing connected to an electrical apparatus and having 3,721,946 Patented Mar. 20, 1973 terminal contacts on opposite ends thereof. One terminal contact has a threaded portion within the bushing, with another portion of such contact extending through the bushing for connection into the internal parts of the electrical apparatus. The other terminal contact is on the outer end of the bushing and provides means to connect the external power cables. A threaded connector member, either solid or fused, extends through the bushing and is threaded to the one terminal contact while electrically engaging the outer terminal contact. A locking plate or disconnect member is provided having one or more power cables connected thereto and having an attaching means to attach the locking plate to the outer terminal. A lip or locking part is provided on the locking plate overlying the outer end of the threaded connector preventing its removal from the bushing. If desired, a bayonet connection may be provided in place of the threaded connection.

The invention which is sought to be protected will be particularly pointed out and distinctly claimed in the claims appended hereto. However, it is believed that this invention and the manner in which its various objects and advantages are obtained as well as other objects and advantages thereof will be better understood by reference to the following detailed description of the preferred embodiments, particularly when considered with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view of a high voltage bushing showing the locking plate according to one preferred form of this invention with the locking plate in locking position;

FIG. 1a is a partial sectional view of the interior end of the high voltage bushing of FIG. 1 showing a bayonet connection;

FIG. 2 is a front view of a bushing similar to FIG. 1 showing the prior art bushing without a locking plate;

FIG. 3 is an enlarged perspective view of the external end of the bushing of FIG. 1 showing another view of one locking plate according to this invention;

FIG. 4 is a perspective view of one preferred form of the locking plate of this invention;

FIG. 5 is a plan view of a solid connector which may be used in the bushing of FIG. 1;

FIG. 6 is an enlarged partial sectional view of the external end of a high voltage bushing showing another form of locking plate in locking position according to this invention; and

FIG. 7 is a perspective view of the form of locking plate shown in FIG. 6.

DESCRIPTION OF PREFERRED EMBODIMENTS In the preferred form of this invention, a hollow bushing is attached to the wall of an electrical apparatus and a removable connector device extends through the bushing providing an electrical connection from one end of the bushing to the other. A locking plate is provided on the outer terminal of the bushing to prevent the removal of the removable connector without removing the locking plate. For a more complete description, reference will now be made to the drawing in which like numerals are used to indicate like parts throughout the various views.

Referring first to FIG. 1, a hollow bushing 10 is shown secured to a wall or cover 12 of an electrical apparatus (not otherwise shown) by means of bolts. 14 which extend through a flange 16 on the bushing 10. Obviously, bushing 10 could be bolted, clamped, or welded to the wall or cover 12 in any other manner desired. As will be understood, Wall 12 forms a portion of a container or tank for an electrical apparatus such as, for example,

a distribution transformer, which is usually sealed and provided with a dielectric fluid, such as mineral oil, for insulation and cooling. Bushing 10 is provided with a first contact or terminal 18 which has a threaded portion 20 mounted in the bushing 10 and a second portion 22 extending through the bushing 10 as shown. As will be understood, the portion 22 extending through the bushing 10 is sealed so as to prevent entry of cooling fluid into the bushing or the entry of any contaminants from the bushing into the cooling fluid. As shown, portion 22 of contact 18 is threaded and is provided with nuts 24 for securing the internal lead (not shown) of the electrical apparatus, as is well understood in the art. The other end of bushing 10 is provided with a terminal plate 26 which forms a second contact of the bushing and is attached to the bushing 10 by spring means 28. A connector member 30 is provided which is inserted into bushing 10. Connector 30 has a threaded portion 32 which makes a threaded connection to the threaded part 20 of contact 18. The opposite end of connector 30 is provided with a cap portion 34 and an eye 36. As will be understood by means of eye 36, a linemans hotstick may be used to insert connector '30 through the opening in terminal plate 26 and thread the end 32 into contact part 20. Cap 34 of connector 30 will cover the opening in terminal 26 and will provide electrical contact to terminal 26.

As shown in FIG. 1, connector 30 includes a fuse element 38 electrically and physically connected between threaded portion 32 and cap 34. As will be apparent by means of eye 36 and a hotstick connector 30 and included fuse 38 may be removed from bushing 10 to allow replacement of fuse 38, or to provide a desired visible disconnect. Of course, if desired, a solid connector 30' could be secured in bushing 10 without the fuse element. FIG. shows one form of a solid connector 30' having a threaded end 32', a cap 34' and an eye 36. Clearly, solid connector 30' could be substituted for fuse connector 30, if desired. Obviously, it could be readily withdrawn to provide a visible disconnect, when desired, by means of the eye 36'.

As earlier noted, when removing connector 30 or 30' even though the transformer has no secondary load, magnetizing current is present which could damage the threaded connection between contact 20 and 32. To prevent such damage, it is desirable to require removal of the high voltage lead prior to removal of connector 30 or 30'.

FIG. 1a shows an alternate connector means for the internal contact of bushing in the form of a bayonet connector a. As is shown in FIG. la, bayonet connector 20a has a flared open end 19' to receive the bayonet contact 32a of connector 30. A spring member 21 surrounds the flared contact 19 providing continuous pressure on bayonet contact 32a, as is well understood by those skilled in this art. Obviously, connector could also be used as a bayonet contact.

FIG. 2 shows the front or top view of a bushing 10 as is usually found in the prior art. The terminal plate 26 has a slot 40 to receive a terminal connector 42 carrying the high voltage lead 44. As can be seen from FIG. 2, connector 30 can be readily removed without disturbing cable lead 44.

To prevent the removal of connector 30 or 30 while a cable lead is still connected, a locking plate 46 is provided as can be best seen in FIGS. 3 and 4. Locking plate 46 is essentially a Z-shaped member having a locking portion 48 and a cable carrying portion '50 which is joined by the angled portion 52. Cable carrying portion 50 has a slot 54 for attachment to terminal plate 26 by means of eyebolt connector 56. As can be seen from FIGS. 1 and 3, eyebolt connector 56 fits into the complementary slots 40 and 54. A nut 58 on the end of connector 56 fits against a lug (not shown) on terminal plate 26 allowing eyebolt connector 56 to be tightened forcing 4 the cable carrying portion 50 of locking plate 46 and terminal plate 26 against each other. The locking portion 48 of plate 46 is tightened firmly against cap 34, securely locking connector 30 in bushing 10. Also connected to cable carrying portion 50 of locking plate 46 are cable leads 58 and '60. As shown in the drawing, two cable leads are preferred on locking plate 46 since this provides for loop feed service through the locking plate 46. Also, as will be clear, locking plate 46 may be removed from bushing 10 Without interrupting the loop. Of course, it will be understood that only a single cable lead is necessary to provide the desired electrical energy to bushing 10 and, therefore, to the apparatus to which it is connected.

FIGS. 6 and 7 show another form of locking plate according to this invention. FIG. 6 shows a partial sectional view of the bushing 11, similar to bushing 10 and having a connector 31. The terminal plate 27 is secured to bushing 11 by means of a clamping ring 62, secured by a bolt 64. Connector '31 is provided with a cap 35 having an eye 37 in the same manner as connector 30 or 30', and can also be removed by a hotstick. The locking plate 66 is a flat metal member having a large slot 68 which fits around the eye 37 of cap 35. Openings 70 and 72 are provided for eyebolts 74 and 76, which are threaded into terminal cap 27, as shown. Other slots 78 and 80 are provided in locking plate 66 to receive cable leads, such as cable lead 82, shown in FIG. 6. Obviously, a pair of leads can be provided in the manner previously discussed with reference to locking plate 46.

As will be apparent from the above description, locking plate 66 is securely attached to terminal plate 27 by means of eyebolts 74 and 76. Also, it will be apparent that locking plate 66 locks the cap 35 firmly in place against terminal plate 27. By use of a hotstick on eyebolts 74 and 76, looking plate 66 may be readily removed, allowing connector 31 to be Withdrawn by the eye 37. In the embodiment shown, eyebolts 74 and 76 are captive in locking plate 66, allowing them to be threaded into and out of terminal plate 27 without being withdrawn from holes 70, 72, in locking plate 66. Thus, after unthreading the eyebolts 74 and 76 from terminal plate 27, the locking plate 66 can be easily removed by a hotstick in either of the eyebolts 74 or 76.

From the above description, it will be apparent that this invention securely locks the removal connector in the bushing and prevents its removal until the locking plate and high voltage leads are removed from the bushing. The invention which is sought to be protected is set forth in the appended claims.

What we claim as new and desire to secure by Letters Patent of the United States is:

1. A high voltage bushing including a hollow insulator member, means for securing said insulator member to the enclosure of an electrical apparatus with one portion of said insulator member extending into the enclosure, a first contact in said one portion of said insulator member with a contact making part of said first contact internal of said hollow insulator member, a second contact in the form of a terminal plate secured to the exterior end of said insulator, an opening in said terminal plate, a removable connector member extending through said opening into said hollow insulator and having an end for engaging said contact making part of said first contact, said removable connector having a cap portion engaging said terminal plate when said end thereof is secured in said contact making part, and a locking plate to prevent removal of said removable connector, said locking plate comprising a metal member, said metal member engaging said cap portion of said removable connector, and being removably secured to said terminal plate, at least one high voltage lead attached to said metal member.

2. A high voltage bushing as set forth in claim 1 in which said removable connector member is a solid member extending between said end and Said cap portion.

3. A high voltage bushing as set forth in claim 1 in which said removable connector includes a fuse member, said fuse member electrically and physically connected between said end and said cap portion.

4. A high voltage bushing as set forth in claim 1 in which said locking plate is in the form of a Z-shaped member, one part of said Z-shaped member engaging said cap portion and the other part of said Z-shaped member removably secured to said terminal plate, said high voltage lead attached to said other part of said Z-shaped member.

5. A high voltage bushing as set forth in claim 4 in which said terminal plate has a slotted portion and in 'which said Z-shaped member has a slotted portion in said other part and an eyebolt connector mounted in said slotted portions firmly secure said Z-shaped member to said terminal plate.

6. A high voltage bushing as set forth in claim 1 in which said locking plate is in the form of a flat metal member, a pair of eyebolts captive in said member and threading into said terminal plate to removably secure said locking plate to said terminal plate.

7. A locking plate for a high voltage bushing having a terminal plate and a removable connector having a cap, said connector extending from one end of the bushing to the other, and a removing eye on the cap of the connector, said locking plate comprising a flat metal member having a slot for receiving the eye of the connector cap, at least one captive eyebolt in said locking plate for securing said locking plate to the terminal plate, the portion of said locking plate about said slot engaging the cap of the removable connector to lock the removable connector in the high voltage bushing.

References Cited UNITED STATES PATENTS 1,871,748 8/1932 Schramm 339l26 R 3,612,750 10/1971 Monico et a1 339263 R 3,622,946 11/1971 Rogers 339263 R JOSEPH H. MCGLYNN, Primary Examiner US. Cl. X.R.

33992 R, R, 147 R, 263 R 

